Various types of antioxidant additives are used to protect food from oxidation, inhibiting the effect of oxygen in the atmosphere. Natural preservatives, such as soluble vitamin C (ascorbic acid and its salts with sodium, calcium, etc.), may be used to protect some fruits or meat, or while ascorbic stearate or palmitate are used as oil or fat soluble antioxidants for use with other foods. Ascorbic acid (Vitamin C) and tocopherols (a class of compounds with Vitamin E activity) are the most important commercial natural antioxidants, but they are expensive and unstable in processing and storage at high temperatures.
The expense of current natural preservatives limits their broader use in foods, leading to continued use of synthetic preservatives. Synthetic anti-oxidants include BHT (butylated hydroxytoluene), TBHQ (t-butyl hydroquinone), BHA (butylated hydroxy anisole), gallic acid, and gallic esters. The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among academics and regulators specializing in food science and toxicology.